How to organize an asymmetric UDP connection using Mikrotik?

Question

SIP

Is it possible to somehow connect a network device behind NAT with an external address using Mikrotik, provided that the device itself sends packets from a random port, and waits for a response on a fixed port?
In more detail, I have cisco 7911 phones and a virtual IP PBX MANGO. As I did not try to achieve otherwise from both, it only turns out that the phone sends packets from a random port to 5060 (the port is configured in the phone). And Mango answers him on the port from which the packet leaves and nothing else. At the same time, due to the "features" of this tsiska model, as I understand it, the phone only waits for a response to the configured SIP port (5060 by default). Flashing and reconfiguring the phone does not change the situation in any way. Mikrotik stands in the middle and redirects UDP packets from the phone to Mango, and sends response packets to the port of origin of the phone. I’m wondering if it’s possible to make Mikrotik with mango send response packets to port 5060 of the phone? In the SIP packets themselves, the phone puts its contact with an external IP with port 5060, but the mango server ignores this, apparently deciding,
Technical support Mango simply answers that the phone is not supported of course.

Answer 1

Already toiled with these devices - there were half an office of such. There is such an article, but this setting did not help me - Cisco has its own idea of ​​\u200b\u200bNAT. https://voxlink.ru/kb/ip-phones-configuration/cisc...
A reliable option is to drive the connection through a sip proxy in the local network (this was decided before moving to your own PBX). The simplest proxy option that solves this problem is siproxd

Answer 2

Is it possible to configure the device that sends packets to a specific port for a device that is behind nat, so that it sends an external ip to a fixed port, and on a device with external ip do port forwarding for a device that is behind nat with a fixed port? If not, raise a tunnel to your device that sends packets to a fixed port, advertise your gray networks in it.